Restoring Individual Tables Restoring Individual Tables¶
In server versions prior to 5.6, it is not possible to copy tables between servers by copying the files, even with innodb_file_per_table. However, with Percona XtraBackup, you can export individual tables from any InnoDB database, and import them into Percona Server with XtraDB or MySQL 5.6. (The source doesn’t have to be XtraDB or or MySQL 5.6, but the destination does.) This only works on individual .ibd files, and cannot export a table that is not contained in its own .ibd file.
Let’s see how to export and import the following table:
CREATE TABLE export_test (
a int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
Note
If you’re running Percona Server version older than 5.5.10-20.1, variable innodb_expand_import should be used instead of innodb_import_table_from_xtrabackup.
Exporting the Table¶
This table should have been created in innodb_file_per_table mode, so
after taking a backup as usual with --backup, the .ibd file
should exist in the target directory:
$ find /data/backups/mysql/ -name export_test.*
/data/backups/mysql/test/export_test.ibd
when you prepare the backup, add the extra parameter --export to the
command. Here is an example:
$ xtrabackup --prepare --export --target-dir=/data/backups/mysql/
Now you should see a .exp file in the target directory:
$ find /data/backups/mysql/ -name export_test.*
/data/backups/mysql/test/export_test.exp
/data/backups/mysql/test/export_test.ibd
/data/backups/mysql/test/export_test.cfg
These three files are all you need to import the table into a server running Percona Server with XtraDB or MySQL 5.6.
Note
MySQL uses .cfg file which contains InnoDB dictionary dump in
special format. This format is different from the .exp` one which is
used in XtraDB for the same purpose. Strictly speaking, a .cfg`
file is not required to import a tablespace to MySQL 5.6 or Percona Server 5.6. A tablespace will be imported successfully even if it is from
another server, but InnoDB will do schema validation if the corresponding
.cfg file is present in the same directory.
Importing the Table¶
On the destination server running Percona Server with XtraDB and innodb_import_table_from_xtrabackup option enabled, or MySQL 5.6, create a table with the same structure, and then perform the following steps:
- Execute
ALTER TABLE test.export_test DISCARD TABLESPACE;- If you see the following message, then you must enable
innodb_file_per_table and create the table again:
ERROR 1030 (HY000): Got error -1 from storage engine
- If you see the following message, then you must enable
innodb_file_per_table and create the table again:
- Copy the exported files to the
test/subdirectory of the destination server’s data directory - Execute
ALTER TABLE test.export_test IMPORT TABLESPACE;
The table should now be imported, and you should be able to SELECT from it
and see the imported data.
Note
Persistent statistics for imported tablespace will be empty until you run the
ANALYZE TABLE on the imported table. They will be empty because they are
stored in the system tables mysql.innodb_table_stats and
mysql.innodb_index_stats and they aren’t updated by server during the
import. This is due to upstream bug #72368.
